March 27th, 2011 – Salt effects on molten core materials – Effects on energetics

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From: Lee, Richard
To: Hoxie, Chris; Uhle, Jennifer
Cc: Gibson, Kathy
Sent: Sun Mar 27 10:35:35 2011
Subject: RE: Brian’s Q
Consulted both Mike and Dana on the matter – Salt effects on molten core materials:

From Mike Corradini:

This will not likely generate a more energetic effect. It will be a dilution to the melt composition and energy.

Think of this like any solid that must be melted and mixes with the melt. So no effect there. So if it does stop the melt there with in-vessel retention (which I suspect it would), it would add to the melt volume as it remelts and mixes and dilutes the corium.

I would then expect it to lower the solidus temperature of the mixture. How much, I do not know, but we can see the effect on energetics by altering the solidus. Remember that the if we assume triggering (which we always do), steam explosions are a thermodynamic phenomenon altered minimally by local heat transfer.


From: Dana Powers

Core debris will hit the salt and cause it to melt and vaporize.

Some fraction of it will be incorporated into the core debris, but much will vaporize – removing heat from the core debris.

Vaporized salt will condense on upper internals of the BWR vessel.

Salt in the core debris will cause some vaporization of materials – including some fission products – as chlorides, but I would not expect the effect to be especially significant.

Again vaporized chlorides will condense on upper internal surfaces.


From: Hoxie, Chris
Sent: Saturday, March 26, 2011 9:41 PM
To: Uhle, Jennifer
Cc: Lee, Richard; Gibson, Kathy
Subject: Brian’s Q

In regards to Brian’s question about how salt water may influence the dynamics of a fuel coolant interaction:

Here are two references:

http://www.iaea.org/inis/collection/NCLCollectionStore/ Public/42/006/42006251.pdf

On page 396, states that pure water vs. salt water made no difference in an experiment designed to measure peak pressures for fuel coolant interactions in a lab setting.


Reference 2:

Although it might not be one-for-one, here is a reference to research that indicates the salt might actually dampen the steam explosion (or at least it does maybe when lava hits sea water…. )

Caveats: This reference 2 is not nuclear oriented. Not specific to the Japan case. This is really complex and should be answered by an expert. Depends so much on the actual conditions in the Japan plants…

At least I did not find anything that says salt makes things worse!

Impure coolants and interaction dynamics of phreatomagmatic eruptions

James D. L. White
Geology Department, University of Otago P.O. Box 56, Dunedin 9015, New Zealand
Received 12 January 1996;
revised 18 June 1996;
accepted 18 June 1996.
Available online 26 February 1999.

Abstract

Phreatomagmatic eruptions resulting from interaction of magma with groundwater are common in many terrestrial settings, and their explosivity is widely accepted to result from fuelcoolant interaction (FCI) processes.

Relatively little attention has been given to the precise nature of the volcanic settings in which phreatomagmatic FCI’s take place, but several lines of evidence indicate that they almost inevitably involve mixing of magma with impure, sediment-laden water.

Consideration of the effects of these impure coolants on the fuel-coolant interaction process suggests that:
(1) impure coolants enhance the ability of magma to mix with large volumes of coolant; and
(2) maximum unit-volume explosivity of FCI’s is damped relative to interactions with pure water.

It is probably unrealistic to back calculate water-magma mass ratios for most, if not all, phreatomagmatic eruptions because:

(1) effects of impure coolants on fragmentation efficiency and eruption explosivity are not yet known; and
(2) aspects of the vent environments in which phreatomagmatism occurs may influence fragmentation processes, explosive efficiency, and resultant particle populations as or more strongly than water-magma mass ratios.

To estimate mass ratios for individual bursts, or for eruptions as a whole, one must distinguish particle populations resulting from many different processes in phreatomagmatic vents, including primary fragmentation, induced fragmentation, vent-wall collapse and pyroclast recycling.

Incorporation of accidental blocks beyond the zone of phreatomagmatic interaction and ejection of unvaporized water further complicate efforts at reconstruction.


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